Security updates for Friday

Security updates have been issued by Arch Linux (dovecot and imagemagick), Debian (dovecot, libraw, pdns, and ruby2.1), Fedora (mingw-podofo, openwsman, podofo, qemu, and svgsalamander), openSUSE (chromium, ffmpeg-4, firefox, libssh2_org, nodejs4, and qemu), Red Hat (libssh2), Scientific Linux (libssh2 and thunderbird), SUSE (kernel, liblouis, ntp, openssl-1_1, and tiff), and Ubuntu (firefox, freeimage, libapache2-mod-auth-mellon, and thunderbird).